Multi-stage pipeline

[cveld]

With terraform we use a multi-stage pipeline that first establishes a terraform plan, and after review, kicks off terraform apply.
It is fairly easy to transition a terraform plan to a fresh apply stage, by copying the lock file and the plan file, run init and then apply.

How can I do the same with terragrunt?

Additionally, this multi-stage approach should ideally be taking place per group of modules.

E.g.
Group 1

• baseline1
• baseline2

Group 2

• extension1
• extension2

Group 3

• module1
• module2

The stages should be doing the following:

• Plan 1: yield a plan against all groups. validation: no errrors
• Approval check
• Apply 1: apply group 1. validation: no errors
• Plan 2: yield a plan against all groups. validation: no errors, and group 1 should not contain changes
• Approval check
• Apply 2: apply group 2. validation: no errors
• Plan 3: yield a plan against all groups. validation: no errors, and group 1 and 2 should not contain changes.
• Approval check
• Apply 3: apply group 3. validaton: no errors

Is this possible?

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Tracked in ticket #110638

[gitsstewart]

@cveld Have you already looked through the Terragrunt docs? https://terragrunt.gruntwork.io/docs/
Without more information I'm not sure if the auto-init functionality might be the answer to your question:
https://terragrunt.gruntwork.io/docs/features/auto-init/

[cveld]

@gitsstewart I am not sure I can follow your idea here. Are you proposing to disable auto-init? Maybe that is something to try out indeed. With auto-init disabled, I can try to copy the generated files from the plan-stage to the apply-stage and rerun terragrunt init. In that way it is parallel to what we are doing for vanilla terraform.